1. Field of the Invention
The present invention relates generally to methods for manufacturing hard disk drives, and particularly to methods for reducing the number of writing defects in magnetic thin film hard disks by optimizing the orientation of the disks prior to disk drive assembly.
2. Description of the Prior Art
The manufacturing of hard disk drives involves many processing steps which are beneficially automated to increase throughput and reduce the cost of the ultimate hard disk drive end product. During the manufacturing process, groups of disks are mounted in carriers for processing, and the orientation of the carriers, and therefore the disks within the carriers is a known process parameter throughout all processing steps, and that orientation is repeated for all processed disks. That is, the orientation of the disks is consistently controlled throughout the hard disk manufacturing process from the first loading of initial disk substrates through the cleaning processes, through the thin film deposition processes, and ultimately through the mounting of the disks upon the hard disk drive spindles.
During certain manufacturing processing steps, particularly the disk washing steps, non-random arcuate submicron sized surface scratches, or micro-scratches, are often formed on the disk surfaces. These micro-scratches have resulted in an unacceptably high percentage of defective disk drives where the micro-scratches produce too many defective magnetic data bits in the surfaces of the individual hard disks of the disk drive. While altering the disk processing devices to reduce the occurrence of such micro-scratches is possible, this is an expensive solution. There is therefore a need in the disk drive manufacturing industry for a method of reducing the number of hard disk defects without reducing the occurrence of micro-scratches on the disk surfaces.